Are you sure about that? I just testet removing a localization for a language in Project > Info > Localizations and it did not remove the language from the string catalog.

Well that's a bummer! I sent feedback... I hope transferCurrentComplicationUserInfo() works with WidgetKit soon enough, the lack of it kind of makes my complication too unreliable atm. Have a good one and thank you!

Is there any update regarding this?